Biology subjects

Fang, S.-C.

Publications and source records attributed to Fang, S.-C..

2 recordsLinked to original sources

bioRxiv2023

A chloroplast sulfate transporter modulates glutathione-mediated redox cycling to regulate cell division

Glutathione redox cycling is important for cell cycle regulation. However, the underlying mechanisms remain unclear. We previously identified a cell-size mutant, suppressor of mat3 15-1 (smt15-1), that has elevated cellular glutathione, increased number of cell divisions, and small daughter cells. Here, we demonstrated that SMT15 is a chloroplast-associated membrane protein that is capable of transporting sulfate. Reducing expression of{gamma} -GLUTAMYLCYSTEINE SYNTHETASE, which encodes the rate-limiting enzyme required for glutathione biosynthesis, corrected the size defect of smt15-1 cells. Moreover, overexpressing GLUTATHIONE SYNTHETASE recapitulated the small-size phenotype of smt15-1 mutant, confirming the role of glutathione in modulation of the cell division. Hence, SMT15 may regulate chloroplast sulfate concentration to modulate cellular glutathione levels. Interestingly, glutathione was found to accumulate in the cytosol at the G1 phase and its level decreased substantially as cells entered the S/M phase in wild-type cells. Even though cytosolic glutathione of the small-sized mutants, smt15-1 and GSH2 overexpressors, followed the pattern of wild-type cells being accumulated at G1 and declined at the S/M phase, the basal body-specific accumulation of glutathione was associated with only the small-sized mutants. Therefore, we propose that glutathione-mediated redox in the basal bodies may regulate mitotic division number in Chlamydomonas reinhardtii. Our results support the link between glutathione-mediated redox regulation and mitotic cell division and suggest a new mechanism through which glutathione regulates the cell cycle. One sentence summaryGlutathione-mediated redox regulation in basal bodies is important for cell division control

cell biology↗

bioRxiv2019

Sustained modulation of emotion-related fibers after 8 weeks of mindfulness-based stress reduction training

An 8-week mindfulness-based stress reduction (MBSR) program enables novices to learn and practice mindfulness meditation. A longitudinal study design has been used in prior research to investigate the effect of short-term mindfulness meditation training on brain structures. Many studies have demonstrated microstructural changes in the white matter by comparing baseline measurements with measurements obtained immediately after short-term meditation training. However, these studies did not clarify the evolution of the modulated microstructures several months after mindfulness meditation practice is discontinued. Therefore, in this study, we recruited 13 novice practitioners and administered an 8-week MBSR training program. We extended the span of the longitudinal study by adding a third measurement taken approximately 6 months after the second time point. Diffusion indices derived from diffusion spectrum imaging were used to quantify the temporal changes in modulation across three time points. The analysis identified four tract bundles that were significantly modulated after the 8-week MBSR training program, namely the callosal fibers connecting the bilateral amygdalae and bilateral hippocampi, right thalamic radiation of the auditory nerve, and right uncinate fasciculus. At the third time point, at which the participants had discontinued practice for approximately 6 months, the diffusion indices of the four tract bundles still presented a significant difference compared with the baseline. Our results indicate that the modulation of microstructural properties of the white matter tract induced by the 8-week MBSR program was sustained after completion of the program and support that neuroplasticity in brain connection persists after the discontinuation of meditation training.

neuroscience↗